Container



Oct. 15, 1968 J. E. HLIJDSON 3,405,831

CONTAINER Filed Sept. 19, 1966 v 2 Sheets-Sheet 1 INVENTOR.

J' E. HUDSON BY I ATTORNEYS Oct. 15, 1968 J E, HUDSON 3,405,831

CONTAINER Filed Sept. 19, 1966 2 Sheets-Sheet 2 INVENTOR.

J. E. HUDSON U QP M' A T TORNEVS United States Patent 3,405,831CONTAINER Jimmie E. Hudson, Bartlesvilie, Okla, assignor to PhillipsPetroleum Company, a corporation of Delaware Filed Sept. 19, 1966, Ser.No. 580,304 8 Claims. (Cl. 215-43) ABSTRACT 0F THE DISCLOSURE A plasticbottle is formed with flexible protrusions extending radially outwardfrom the thread section which cooperate with a smooth surface on a capso as to form a reusable locking device. These flexible protrusions maytake the form of a plurality of tabs projecting outwardly from theridges of the threads or may take the form of a Web extending across thethreads.

This invention relates to plastic containers with screw caps.

The advent of tough, chemically resistant plastics has made possiblepackaging many materials in plastic containers which were formerlypackaged in containers of glass, metal, and the like. With theavailability of clear bottles made of poly (vinyl chloride), orientedpolypropylene, polycarbonate, and the like, plastics have taken on arenewed importance as a container material. Many of these plasticmaterials which are otherwise desirable materials for the fabrication ofcontainers exhibit a very low coefiicient of friction. Indeed suchplastic materials as polyethylene, polypropylene, and nylon arefrequently used as self-lubricating bearings because of their naturalslippery nature. Thus it is not surprising that this property creates aproblem with containers using screw-on caps in that the caps tend tounscrew during shipping or handling. The prior art discloses means tocombat this problem but these means have generally been complex andcumbersome. Furthermore they have frequently been of such a nature thatwhen the cap is first unscrewed the locking device is broken and thus isnot effective to prevent the cap from coming unscrewed when it isreplaced on the container.

It is an object of this invention to provide a plastic container with asimple means which allows a cap to be screwed on easily and yet whichresists any tendency of the cap to come unscrewed.

It is a further object of this invention to provide a plastic containerwith a means which allows a cap to be screwed on easily and yet whichresists any tendency of the cap to come unscrewed, wherein said means isequally effective after the cap has been removed repeatedly.

It is a still further object of this invention to provide a containerwith a locking means which also serves as a seal.

In accordance with this invention a bottle is formed with flexibleprotrusions, extending radially outward from the thread section, whichcooperate with a smooth surface on a cap so as to form a reusablelocking device.

In the drawings forming a part hereof, in which like referencecharacters indicate corresponding parts in all views:

FIGURE 1 is a perspective view of the upper portion of a container madein accordance with one embodiment of this invention;

FIGURE 2 is a sectional view taken on line 22 of FIGURE 1;

FIGURE 3 is a sectional view of the thread section of a container madein accordance with this invention similar to FIGURE 2 except that a capis affixed to the container;

3,405,831 Patented Oct. 15, 1968 FIGURE 4 is a sectional view taken online 4-4 of FIGURE 3;

FIGURE 5 is a perspective view of the upper portion of a container madein accordance with an alternate embodiment of this invention, and

FIGURE 6 is a perspective view of the upper portion of a container madein accordance with an alternate embodiment of this invention.

Referring now to the drawings, a container 1 has a body portion 2 and athread section 3, said thread section having screw threads 4 providedwith flexible tabs or protrusions 6 extending radially outward from theridges of said threads.

FIGURES 3 and 4 illustrate the way the flexible tab is folded backagainst thread 4 when cap 7 is screwed into place. Cap 7 has adownwardly projecting annular skirt or wall 8 and thread grooves 9 whichcooperate with thread ridges 4.

FIGURE 5 illustrates an alternate embodiment in which the outwardlyextending protrusion is in the form of a web 10 which projects radiallyoutward from the thread sect-ion of the container. This web extends overthe ridges of the threads as does tab 6 but also extends across thegrooves of the threads.

FIGURE 6 illustrates an alternate embodiment in which the threads are inthe form of discontinuous lugs 14.

As the cap is screwed onto the container the flexible tabs 6 are foldedback against the threads 4 providing little resistance to the turning ofthe cap; however, after the cap is screwed on any attempt to unscrew itwill result in the flexible tabs buckling and thus forming a wedge whichresists further unscrewing. Since the locking is partially effected bythe wedging of the buckled tab between the thread sections of thecontainer and the cap, notches or catches do not have to be present onthe cap. Thus these bottles can use standard caps, and said caps canhave a smooth inner surface.

The degree of resistance to unscrewing can be controlled by varying thelength and/or thickness of the protrusions either alone or incombination with varying the tolerance between the cap and the containerneck. Generally the protrusions will extend radially outward a distanceequal to between 5 and percent of the depth of the threads, preferablybetween 15 and 30 percent; the thickness of the protrusions willgenerally be from 5 to 50 percent of the radial length, preferably from15 to 25 percent.

The act of unscrewing the cap does not destroy the locking mechanism;thus, as often as it is desired to replace the cap, the lockingmechanism is effective to resist the caps being unscrewed. In instanceswhere it is desired to provide the locking feature only up to the timethe cap is first removed, the flexible project-ions can be trimmed offafter the initial removal of the cap.

The containers of this invention are preferably fabricated by a blowmolding technique, for instance by blowing a freshly extruded parisonout against a mold or by forming parison blanks which are reheated andblown out against a mold. Alternatively they can be made by anyconventional molding means such as injection molding or powder molding.

The flexible locking projections are preferably formed as the containeris made thus avoiding the necessity of any extra steps. When using theblow molding techniques the projections can be formed by the action of asplit sleeve which forms the neck. This split sleeve pinches out aportion of the parison between the two halves at the parting line. Thissplit sleeve may be a separate entity or it may be an integral part of asplit mold. Or in embodiments where a mandrel is inserted into theparison to force the plastic to conform to the shape of the threadforming sleeve, this mandrel may also force the plastic into recesses inthe inner surface of the thread forming means to form the protrusions.In this latter instance the protrusions do not necessarily have to be atthe parting line. In injection molding or powder molding the mold simplyhas the appropriate recesses to form the protrusions. It is apparentthat in embodiments where the protrusions are formed by pinching part ofthe parison between the split sleeve parts, with a sleeve having twohalves either one or two sets of protrusions are possible. With a sleevesplit into three parts a maximum of three sets of protrusions arepossible. With other means of forming the protrusions any number of setsof protrusions are possible; furthermore, the protrusions can be in avertical row one above the other on each successive thread or they canbe spaced at random around the circumference on the various threads. Theprotrusions may be provided on all the threads, on only part of thethreads, or on only one thread.

The caps used in conjunction with this invention can be formed byinjection molding, vacuum forming, powder molding, or any otherconventional molding means. They may be formed in the same manner as thecontainer on which they are used or they may be formed in a differentmanner; for instance, an injection molded cap will frequently be used ona blow molded container.

The threads can be single or multiple lead. The term thread is meant toinclude all types of lugs or catches which are engaged with a cap byrotating the cap relative to the container whether continuous ordiscontinuous.

While this invention is primarily concerned with bottles and jars, it isapplicable to any type of container having a closure which is engaged byrotating the cap relative to the container.

Any plastic material can be utilized in fabricating the container.Examples of suitable materials include: olefin polymers, particularlypolymers and copolymers of ethylene, propylene, and l-butene; nylon;poly (vinyl chloride); polycarbonates; acetal resins; fluorocarbonpolymers; rubber; and the like. The cap can be fabricated from anymaterial used in the fabrication of caps such as plastics, metal, andthe like.

In the alternate embodiment shown in FIGURE the outwardly extendingprotrusion is in the form of a web across both the ridges and grooves ofthe threads. This arrangement not only provides a locking means but alsoaids in sealing the container to prevent the passage of liquids or gasesinto or out of the container.

The outwardly extending protrusion can be formed in its final state inthe initial forming of the container. Alternatively it can be formed ina rough form in the initial forming of the container and trimmed to itsfinal form in a subsequent operation.

EXAMPLE A polypropylene homopolymer of 0 .905 density (ASTM D1505-60 I)and 4 melt flow (ASTM D1238- 62T Condition L) was extruded into aparison 0.970 inch in diameter. This was programmed so as to give aparison wall thickness of 90 mils in the area to be formed into thethread section and 150 mils in the section to be for-med into the bodyof a bottle. This parison was immediately passed into a water cooledquench sleeve one foot long. The parison was pulled out against theinside of this sleeve by a vacuum. The cooled parison was thentransferred to a heating chamber andheated to a temperature just belowthe melting point of the polypropylene over a period of 18 minutes. Theparison was then removed from the heating chamber by a clamp aflixed tothe bottom end of the parison. Split sleeves with a contoured innersurface to form the threads were brought together around the top part ofthe parison. A portion of the outer surface of the parison was squeezedbetween the two halves of the sleeve at the parting line to form theflexible projections. A mandrel was then inserted into this top part ofthe parison; this mandrel forced the plastic to conform more completelyto the shape of the inner surface of the split sleeve thus forming thethreads and neck portion of the bottle. The bottom of the parison waspinched simultaneously with the formation of the threads. The parisonwas then transferred into a split cavity mold, the mold closed and fluidpressure introduced into the mold to force the parison out against themold surfaces, thus producing a 12 ounce oriented polypropylene bottlewith flexible projections on the threads.

While this invention has been described in detail for the purpose ofillustration, it is not to be construed as limited thereby but isintended to cover all changes and modifications within the spirit andscope of the invention.

I claim:

1. A plastic container adapted to be closed with a screw cap,comprising: a body; and a thread section, said thread section having atleast one thread and at least one outwardly extending flexibleprotrusion in the form of a web which extends across the thread ridgesand grooves.

2. A container according to claim 1 wherein said at least one thread iscontinuous.

3. A container according to claim 1 wherein said web extends radiallyoutward from a ridge of said at least one thread a distance equal tobetween 5 and percent of the depth of the threads.

4. A container according to claim 1 wherein the material comprising thecontainer is a polymer of at least one monomer selected from the groupconsisting of ethylene, propylene, and l-butene.

'5. A container according to claim 1 wherein the material comprisingsaid container is polypropylene.

6. A container according to claim 1 in combination with a cap. i

7. A container according to claim 6 wherein said cap has a smooth innersurface.

8. A plastic container adapted to be closed with a screw cap,comprising: a body; a thread section, said thread section having atleast one thread; a plurality of flexible integrally molded protrusionsextending outwvardly from a ridge area of said at least one thread.

References Cited UNITED STATES PATENTS 1,365,884 1/1921 Bayne 28-5922,169,686 8/1939 Fabrice 215' 44 2,355,486 8/1944 Tinnerman 151142,886,089 5/1959 Schlage l5l--25 3,158,553 11/1964 Carski 215-443,295,708 l/ 1967 Wathen 215-43 WILLIAM T. DIXSON, IR., PrimaryExaminer.

